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The mystery of discordance

Silas Masindi was not entirely surprised by his HIV test results. The dapper garment trader, who discovered earlier this year that he was infected with the Aids virus, admits to using condoms somewhat erratically before he remarried three years ago. "I would meet a girl, use a condom, but after four months stop using them," he says.

Silas Masindi* was not entirely surprised by his HIV test results. The dapper garment trader, who discovered earlier this year that he was infected with the Aids virus, admits to using condoms somewhat erratically before he remarried three years ago.

“I would meet a girl, use a condom, but after four months stop using them,” he says.

But surprisingly his second wife, Grace, does not have the virus. The pair have joined other couples who have a mismatched HIV status, something also known as HIV discordance.

Between 13% and 36% of couples in South Africa may be in discordant relationships, says Dr Sinead Delany-Moretlwe of the reproductive health and HIV unit at the University of the Witwatersrand.

However, researchers have yet to understand fully why the Aids virus is not transmitted between these partners, even when they fail to practise safe sex. “It’s such a new concept, even medical people are baffled by it,” says Dr Mamazane Maduna, also with the unit.

What scientists do know is that HIV discordance is related to a combination of factors that include genetics, HI-virus type, the extent to which the infection has progressed in the HIV-positive partner, other sexually transmitted diseases and circumcision—which research indicates may reduce the risk of HIV infection.

“The virus is not systematically transmitted at each and every sexual encounter and depends on how far the HIV-positive person is in the progression of his condition,” says Zimbabwe-based Dr Alexander Boon of the Spanish chapter of the NGO Doctors Without Borders.

A study is under way in six African countries, in a bid to unravel the mysteries of HIV discordance—in particular, whether treating the virus that causes genital herpes reduces the risk of HIV transmission between those in discordant relationships.

“What we know about herpes is that it seems to have a special relationship with HIV,” says Delany-Moretlwe, who—together with Maduna—is assisting with research. A person with herpes is believed to be three times more likely to become infected by HIV.

Conducted in partnership with the University of Washington with funding from the Bill and Melinda Gates Foundation, the study is being carried out at 13 sites in South Africa, Botswana, Kenya, Uganda, Zambia and Rwanda.

South Africa has three sites, one at Orange Farm, a sprawling informal settlement located just south of Johannesburg. Since the programme began in August last year, 314 couples have been tested there, 80 of which were HIV discordant. Thirty-seven of the discordant couples are now participating in trials.

As biological and social factors are known to increase women’s vulnerability to HIV, the assumption might be that it is typically the man in discordant relationships who is HIV-negative. However, HIV infection occurred equally among men and women in discordant relationships who were tested at Orange Farm.

Problems arise with what Delany-Moretlwe describes as “testing by proxy”, where someone may assume they are free of HIV because their partner tested negative.

But in the course of ascertaining HIV status, extensive pre-test and post-test counselling of couples can help discordant partners to stay together. “They seem very supportive of each other,” says Delany-Moretlwe. “People become protective of their partner.”

Silas and Grace appear set to remain a couple. “You know we are happy, very happy together,” says Grace.

She has even accepted that her husband may die sooner than he otherwise would have. “I’m ready for whatever comes,” she says. “What kills people is not accepting.”

Since testing positive Silas has stopped drinking, save for the occasional glass of non-alcoholic wine. He is also more open with his finances, says Grace, and willing to plan with her for the future.

Sex, however, only takes place with a condom—even though discordance has prevented Silas from transmitting the virus to Grace in the past.

“It should be planned in order to protect her,” says Silas. “It’s no longer controlled by my feelings.”

But would he have stayed with her if Grace had been the one who tested positive? “I don’t know,” Silas chuckles. “It would have been something about how she approached me.”—IPS